Method and apparatus for controlling the slicing operation



y 23, v1964 c. METZLER I 3,142,323

' METHOD AND APPARATUS FOR CONTROLLING THESLICING OPERATIQN Filed s- '2 1961 I I v '2 sheets-sheet, 1g

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July 28, 1964 P. c. METZLER METHOD AND APPARATUS FOR CONTROLLING THE SLICING OPERATION Filed Aug. 22. 1961 2 Sheets-Sheet 2 DC POTENTIAL Vgrd REVOLUTIONS INVENTOR. PHIL/P 04m. METZLER United States Patent 3,142,323 METHOD AND APPARATUS FOR CONTROLLKNG THE SLICING OPERATION Philip Carl Metzler, Park Forest, Ill., assignor to Swift & Company, Chicago, Ill., a corporation of Illinois Filed Aug. 22, 1961, Ser. No. 133,161 11 Claims. (Cl. 146-241) This invention relates generally to a method and apparatus for controlling the feed of a given material in accordance with the volume of material fed past a given point by interrupting the feed after a desired volume of material has passed said point and preferably also after a repeating production operation is performed on said amount, to obtain successive amounts of material having uniform characteristics. More specifically the present invention relates to a method and apparatus for controlling the slicing of material by briefly interrupting a constant rate of feed of said material to a slicing machine in accordance with the volume of material fed into -a slicer at a constant rate, and preferably also in accordance with the position of the element performing the slicing operation, to obtain groups of slices of uniform thickness and total weight; and constitutes an improvement in method and apparatus for slicing materials, particularly food materials such as bacon, into drafts of substantially uniform content.

In the slicing of bacon, for instance, it has been a universal practice to calculate the number of slices of a convenient thickness which will make up a desired weight of product, and to separate slices severed from a bacon slab into groups or drafts of that number of slices of product Thus in the past the actual weight of each draft of slices has depended greatly upon the judgment of an operator making the calculations for a number of bacon slabs, which often varied in dimensions between themselves. Also, individual slabs are not of uniform dimensions throughout, and slices taken from different portions of one slab will vary in surface area. Consequently, it often happens that even where the average number of slices per unit of Weight is accurately calculated for a given slab, groups comprising the calculated number of slices taken from different portions of the slab will be above or below the unit weight.

Because the consumer is to be protected in receiving the represented Weight of material in a package of food, it is manifestly important that each draft of slices amount to at least the represented unit weight. However, at the same time, the processor of the material requires that he not be penalized by overweight drafts which would normally sell at the unit Weight price. Therefore, it has been necessary to manually check weigh each draft of sliced product and make or take weight where under or overweight is indicated, by adding or removing slices. In practice the number of off weight drafts usually far exceeds those on weight, and often amounts to eighty or ninety percent of production.

One suggested improvement for obtaintaing on weight drafts of a selected number of slices is presented in Patent No. 2,768,666, to Garapolo et al., the disclosure of which is included herein by reference. According to that patent, the speed of a feed conveyor in a slicing machine may be regulated in accordance with changes in the vertical dimension of material being sliced. That is, it has been suggested that by sensing changes in height of material being sliced the rate of feed could be appropriately raised or lowered as the height decreased or increased, respectively. Theoretically, as a result of that method, a draft of slices comprising a consumer unit of product totaling a specified weight might contain slices of several different thicknesses; however, as between drafts of the same weight, each would contain the same number of slices and each slice would be of substantially a given weight.

While constituting a noteworthy advance in the slicing art, and a useful attack on the problem of obtaining equal weight drafts consisting of a plurality of slices, the aforementioned prior method and apparatus involves several disadvantages. As a practical matter, the hydraulic feed mechanism utilized in most slicing machines inherently involves a significant lag or delay between changes in force applied to the hydraulic medium and changes in motion of the pusher element actuated thereby. The leg may be best explained as due to the natural cushioning effect of the fluid and the piping system. Thus where any control system is applied, the inherent lag of the hydraulic system must be accounted for.

It has been my experience with control systems for slicing machines of the type described that the aforementioned lag makes it nearly impossible to accurately slice successive groups of equal numbers of slices wherein each group closely approximates a specified weight. When the sensing system determines that a thicker or thinner slice is required it takes an appreciable time for the hydraulic feed to begin to either speed or slow the rate of advancement of the material. Moreover, the change in the rate of feed is not immediate, but requires distinct intervals to slow down or speed up. Thus the adjusted rate of advancement is very difficult to obtain at the exact time that the sensed portion of material undergoes slicing. As a result, the adjustments in feed rate may, and most often do, occur in improper relation to the portion of material being sliced; and the thick or thin slices called for at a given portion of the material are made somewhere else on the material.

Thus where each group is essentially determined by a specified number of variable slices there is little assurance that the given number of successive slices will closely approximate the desired weight. Actual tests have indicated that the spread of weights about the desired op timum, for instance 16 ounces to 16 /2 ounces, Varies widely with that type of control, and most groups must eventually be corrected manually.

Furthermore, as noted, it is possible to produce several different thicknesses of slices within a single draft. From the appearance standpoint alone uneven slices within a package may be undesirable, particularly where the edges are exposed as when shingled, as the consumer often reacts with suspicion as to whether the quantity therein is as represented. Additionally, where the sliced material is to be cooked by the consumer, as for instance with sliced bacon, unequal thickness between slices will result in unequal cooking time; and the consumer will usually be dissatisfied with results upon cooking the contents or partial contents of a package together under the same conditions.

Another disadvantage often found in earlier apparatus, particularly slicing machines having hydraulic feeds, is that unusually thin first and/ or last slices are often produced in a draft. This is due to the fact that the feed control may be interrupted, either automatically or manually when it is thought that a given volume of material has been sliced, and then recommenced after a certain interval without regard for the exact position of the slicing element at the time of interruption or recommencement. Thus, it has not always been a requirement that the distance through which the material feed must travel before making the first or last slice be sufficient to give a uniform slice thickness.

Accordingly, it is a primary object of the present in vention to provide an improved method and apparatus for controlling the feed of material to a repeating production operation, which is performed on the fed material, in a manner overcoming the aforementioned disadvantages so as to produce substantially uniform quantities of material.

It is another object of this invention to provide an improved method and apparatus for controlling a material feed in accordance with both the actual amount fed and the condition of a production operation repeatedly performed upon the material.

It is a further object of this invention to provide an improved method and apparatus for controlling the feed in a slicing machine to more efficiently produce drafts of slices totaling at least a given weight of material, each slice having uniform thickness.

Basically this invention involves the control of periods of production by determining continuously the volume of material passing a given point at a steady rate of speed, and interrupting the feed of material upon satisfaction of the following conditions, namely that 1) a given volume has passed that point, and preferably also that (2) a given production operation has been completed upon that volume. This is accomplished by producing a continuous, increasing signal representing the volume of material passing a given point adjacent the location at which the repeating operation is performed; and also preferably producing a momentary signal of constant magnitude once during each cycle of the repeating operation and totalizing the two signals. Up the level of said signals reaching an established value, which is selected to represent a quantity just in excess of the desired amount making up a given draft, advancement of the material to the repeating operation is interrupted. The period during which advancement of the material is arrested may be adapted, duration-wise, to permit ready removal of the preceding material, before recommencing operations upon further material.

Where utilized the momentary signal is of a magnitude selected to bring the sum of that signal and the increasing signal to the established level at the time that the desired quantity of material has passed the given point; but insufiicient to attain the established level before all but the final slice of material has passed that point. Also, the momentary signal is applied at a time related to the repeating production operation so that the established level is reached after one full operation and before the commencement of a succeeding operation.

A similar momentary signal may also be subsequently utilized to initiate recommencement of the feeding of material, after an appropriate delay, so as to insure that the proper amount of material is fed past the point before a first production operation is undertaken on another given volume of material.

An apparatus devised for carrying out the preceding preferred method comprises, generally, a signal producing means responsive to a dimension of the material being fed, and changes therein; and an integrating means for receiving the signal and integrating it with respect to a function representing the rate of feed, so as to produce a further signal which is directly proportional to the amount of material having been fed past the signal producing means. A second signal producing means is located to develop a constant level signal momentarily during the cycle of a repeating operation performed on the material. The momentary signal from the latter means is impressed, along with the integrated signal, upon a detecting means which is set to change conditions upon the total of said signals reaching an established value. Such change in condition of the detecting means ends the period of production.

The detecting means in turn is connected to control the material feed apparatus so that, upon the change in condition of the detecting means, feeding of the material is interrupted.

Additional components similar to the aforementioned integrating and detecting means may preferably be associated with those components, along with a constant signal means, to provide a standard of comparison and overcome the first mentioned detecting means to reinitiate the feeding of material at established intervals of greater duration than the longest expected period of production necessary to process the largest expected amount of material for a given application of the invention.

One embodiment of the invention, applied to a bacon slicing apparatus, has been illustrated in the accompanying drawings, but it is to be expressly understood that said drawings are for purposes of illustration only and are not to be taken as a definition of the limits of the invention, reference being had to the appended claims for that purpose. In said drawings:

FIGURE 1 illustrates an electrical control circuit containing all of the preferred elements;

FIGURE 2 is a representative graph showing signal voltages plotted against time with respect to the detecting means in the circuit of FIGURE 1; and

FIGURE 3 is a perspective view illustrating a bacon slicing machine equipped with the control system of the present invention.

The material to be operated upon is advanced at a constant rate and in a given direction to the location at which the repeating operation is carried out. The specific apparatus by which the material is advanced is immaterial to this invention; however, for purposes of disclosure a hydraulically operated pusher is utilized, and advancement of the material is controlled by blocking and unblocking the flow of hydraulic fluid to an operating cylinder actuating the pusher.

To practice the present method, one or more dimen' sions, as necessary, of the material being fed is observed at a point just in advance of the location at which the repeating operation is carried out. A variable signal representing the dimensions, and variations therein, is continuously produced from the observations at that point and continuously integrated against a function of the rate of feed. Where the rate is constant, this may simply be a straight time function.

Preferably a DC voltage is employed as a variable signal increasing or decreasing about a convenient base voltage according to increases and decreases in the observed dimension, respectively. Integration of such a signal may be conveniently and preferably accomplished in an amplifier circuit such as that illustrated in FIG- URE 1 wherein a capacitance is placed across the input and output of the amplifier.

Accordingly, integration of the dimensional signal will result in a constantly increasing signal emanating from the amplifier means (an increasing DC. voltage in the preferred embodiment). The increasing signal will be a direct function of the volume of material passing the point of observation.

Simultaneously, the repeating operation is preferably utilized to generate a momentary and constant signal once during each cycle of operation. In the art of bacon slicing, the repeating slicing operation is performed by a blade, usually an involute blade rotating at constant speed. In this instance the momentary signal is caused to be generated at an instant between successive periods that the blade actually passes through the path of the material being sliced.

This signal may most conveniently be generated by a momentary contact type switch placed across a source of constant D.C. electrical potential.

The integrated and momentary signal are continuously applied to a detecting means which has the characteristic of undergoing a detectable physical change upon the combined signals reaching an established level or condition. Thus by setting the established level so that the physical change occurs only upon the integrated signal reaching a level representing a desired volume of material to be operated upon, and the correct or a compensated position of the operating means to indicate it is between operations, the change of state in the detecting means can be observed and utilized to interrupt the feeding apparatus. The detecting means may take the form of a thyratron tube or a semi-conductor such as a transistor, or some other electrical valve wherein a condition of nonconductance may be changed to one of conductance upon the manipulation of minor control voltages such as the aforementioned D.C. voltage signals.

In the embodiment disclosed a thyratron tube is utilized as a detecting means, and upon receiving the appropriate signals it will cause an electrical circuit to be established to a solenoid actuating a control valve in a hydraulic line to a hydraulic feed.

According to the preferred method, a separate and continuous constant signal is introduced to a further integrating means to thereby produce another integrated signal representing a constant reference for the feeding cycle. This signal continues to increase from the start of one period of advancement to a moment just before the start of a subsequent period of advancement. Actual duration of this cycle may be adjusted by regulating the level of the continuous and constant signal to the further integrating means. In eifect, the integrated signal represents an imaginary volume of comparison larger than any expected production volume. Such signal is caused to be commenced at the same time that the variable D.C. voltage signal is impressed upon the first mentioned integrating means (that is, at the time a period of advancement is commenced in the feed cycle), and will continue after the feed has been interrupted. Similarly, a further detecting means is associated with such other integrating means, and is established to change state upon the signal from the latter means reaching a level representing the complete feed cycle interval. In a similar manner the second integrated signal induces a change which is used to reinitiate advancement of the feed.

The preferred method also incorporates a further momentary signal generated by the repeating operation. The latter signal, while generated during each operation on the fed material and those operations carried out while material feed is interrupted is detected, however, only after the second integrated signal reaches the established level indicating the end of a complete feed cycle. Thus in the final analysis the last mentioned momentary signal is utilized in combination with the second integrated signal to permit resumption of the feed only at a certain instant between the performance of one operation and the immediately succeeding operation.

Referring to the electrical circuit of FIGURE 1 representing the control system devised to carry out the aforementioned method and the slicing apparatus of FIGURE 3, the first sensing means generally comprises a plurality of variable D.C. voltage potentiometers 11 which are mechanically connected to a number of followers 12, which are disposed along the path of material 13 being fed. In FIGURE 3, the invention is shown applied to a bacon slicing machine generally 16, of a type similar to that shown in patent No. 2,768,666, comprising a frame 17, having a rotatable involute knife blade 18 mounted thereover; and a hydraulic pusher 19, on the frame disposed to advance bacon slabs into the path of the involute knife blade 18. The followers 12 are disposed above and at one side of the path of a bacon slab closely in advance of the involute knife blade 18, to gauge variations in the thickness and width dimensions of such slabs. The connection between the followers 12 and potentiometers may follow any convenient plan such as, for instance, the structure shown in copending application 650,652 filed April 7, 1957, by B. T. Hensgen et al., now Patent No. 3,105,533, the disclosure of which is included herein by reference. Additionally the plural overhead followers may be mechanically coupled together to produce an average movement which in turn is impressed on a single potentiometer 11.

Returning to FIGURE 1, the potentiometer 11, located along one dimension of the feed material is connected across a D.C. power supply 22 with the variable tap connected to the potentiometer along the other dimension; The variable tap of the latter potentiometer, in turn, is connected to the input terminal 25 of an amplifier circuit generally 26, comprising a pair of stablilizing and operational amplifiers 27, 28 respectively, connected in cascade. A variable resistor 29 is series connected between the amplifier circuit 26 and the potentiometers 11 so that the signal impressed upon the amplifier circuit may be regulated. A capacitor 30 is connected across the input 25 and output 31 leads of the amplifier circuit 26 thereby creating an RC network which causes that circuit to be a production integrating means producing a continuously rising D.C. voltage signal upon the application of a variable D.C. voltage from the potentiometer 11. It will become clear that the rising signal produced by amplifier circuit generally 26 should be positive for application in the illustrated circuit. This may be accomplished in the illustrated circuit, where the amplifier input signal is derived from a B+ source, by providing 360 phase change in the amplifier circuit (or the circuit may be altered to connect potentiometers 11 to the B- source and provide phase change in the amplifier generally 26). The rising signal will, however, vary in rate of increase, in accordance with variations, in dimensions of the bacon slab. Also re sistor 23 controls the maximum voltage obtained over a given time period.

The input 25 and output 31 leads from the production integrating means are connected to opposite terminals on a first switch 35 of a first D.C. powered solenoid relay 34 and also to another switch (97) parallel to switch 35, to be later described. Thus either of the aforementioned switches when closed will short out the production integrator circuit and render it inoperative. Also connected to the integrator output lead is a grid 38 of a first gas filled thyratron tube 36.

The aforementioned first D.C. relay solenoid 34 is connected between a plate 37 of the first thyratron tube 36 and a B+ terminal of the D.C. power supply 22. The connection to the B+ D.C. power terminal is made through a normally closed relay switch (92) associated with a separate relay to be later explained. For the present it should be observed that the normal potential on the plate of the first thyratron, while unfired, is the B+ value. Current, however, will not flow to the plate and thus to the solenoid of the first relay 34 until the gas-filled thyratron becomes ionized and changes from a nonconductor to a conductor at which time it will fire. This condition will be reached when the potential on the thyratron grid 38 approaches the potential on the thyratron cathode 39.

The thyratron cathode 39 in turn is connected throug a potentiometer 40 to the ground terminal of the D.C. power supply 22. Thus the potential normally placed on the cathode 39 is some value above ground potential; However, an additional factor afiecting the cathode potential is interjected by a usual grid leakage circuit comprising a suppressor grid 41 connected in parallel with the cathode 39 through a resistance 42 and to the B+ terminal. Accordingly, the actual potential of the cathode 33 is a function of both the aforementioned resistances 4-0 and 42, and if the resistances are equal, the potential will be one-half the difference between B+ and ground potential.

The potentiometer 40 between cathode and the ground terminal is connected by a lead 43 running from a point on the resistor to the ground terminal through a first momentary action switch 46. The switch 46 is physically attached to the slicing machine generally 16, as may be seen in FIGURE 3, so that it is actuated by a trip lug or magnet 47, mounted on the blade shaft, momentarily each revolution of the involute slicer blade 18 during the interval that the blade is slicing material 13 therebeneath. However, the exact position may vary substantially between different slicing machines according 7 to inherent characteristics, principally lag in the hydraulic feed system.

Thus the momentary effect of the application of ground potential through the switch 46 to a point on the potentiometer 40 closer to the cathode 39 is to reduce the voltage on the cathode and thus at any given time to momentarily reduce the difference in potential between the cathode 39 and the grid 38. The moment that the grid potential sufliciently approaches the cathode potential to overcome the cathode bias the thyratron tube 36 will fire and ionize the gas therein permitting current to fiow between plate 37 and cathode 39. So long as the current continues to flow therebetween, the thyratron will remain ionized regardless of the potential of the grid with respect to the cathode.

The relative cathode and grid potentials in the thyratron are graphically illustrated against revolutions of a slicing machine, the latter being equivalent to time, in FIGURE 2. The rising curve designated Vg represents the potential placed upon the grid 38, which is the increasing signal from the amplifier circuit 26 indicating the volume of material having passed the otentiometers 11. Curve Vg commences at about ground potential (Vgrd) and increases in a positive sense toward the cathode potential designated Vc. As noted, when the grid potential Vg approaches the cathode potential Vc, say within about 2-5 volts thereof, the thyratron will fire. This will be employed to cease the movement of pusher 19 toward the knife 18. Therefore, the potential on cathode 39, with respect to the rate of increase of the grid potential, is established at a level representing the desired volume of a draft of slices. However, the feed system will lag somewhat in response to operation of the appropriate controls, and at normal operating speeds, of about 1300 rpm. in a slicing machine, it is usually found that the blade 18 will complete less than one revolution between a command to stop the feed and the actual time that the pusher ceases movement. Accordingly, at an instant during the operative stroke of the knife 18, a further potential is impressed on the thyratron in the order of a voltage signal representing the volume of a signal average slice. If the total of this further signal in addition to the increasing signal closely approaches the normal cathode level, the thyratron will fire and the slicer will sever the last slice of the draft, and then the feed will stop.

As described, and as may be seen graphically in FIG- URE 2, it is most convenient to impress the additional momentary signal directly on the cathode 39 and reduce the potential Vc by that amount once each revolution of the knife. Thus Vc displays abrupt valleys at points during each revolution of the knife. Normally, the thyratron will be caused to fire when the potential Vg intersects or approaches a valley on the cathode potential Vc. Optimumly, this occurs at the nadir of a valley on Vc, in which case the draft of slices should be almost exactly on weight. Similarly, if the point of intersection or closest approach occurs at a higher point on the valley of Va, the draft will be slightly overweight, but in an amount usually less than the weight of a full slice.

Upon the firing of the thyratron 36 the first D.C. relay solenoid 34 will be energized and in turn will cause the aforementioned first switch 35 to close and short the input 25 and output 31 of the production integrating means. This halts the integrating operation. Integration in this circuit will not recommence until the switch 35 is opened. Actuation of the relay solenoid 34 also closes second, third, and fourth switches, 48, 49 and 50, respectively, on the first D.C. powered relay 34.

The second switch 48, which is normally open, is closed to connect a plate 53 of a second gas-filled thyratron tube 52, and the solenoid of a second D.C. powered relay 55, together in series with the 13+ terminal of the DC. power supply 22. The function of the second 8 thyratron 52 is that of a second detecting means and will be subsequently explained.

The third switch 49 on the first D.C. powered relay 34 has double throw, the first of which, in the normal position when the solenoid of relay 34 is unenergized, connects a production solenoid 57 across an AC. power supply 58 (which in turn operates a fiow control valve, not shown, in the hydraulic feed means to the open position causing the pusher 19 to advance). When the solenoid of relay 34 is energized, however, the third switch 49 is thrown to a second position (thus de-energizing the production solenoid 57) and places a dwell solenoid 59 across the same A.C. power supply to throw the flow control valve to a closed position and cease advancement of the pusher 19.

The fourth relay switch 50, operated by the first D.C. relay 34, is connected in series with a first relay switch 61, operable by the second D.C. powered relay solenoid 55, across input and output terminals 62, 63 respectively, of a second amplifying circuit generally 64 connected to operate as a dwell integrator.

The second integrating means is basically the same as the first integrating means and comprises a stabilizing amplifier 65 and an operational amplifier 66 connected in cascade. A constant and continuous signal is impressed upon the input 62 to the amplifier circuit generally 64 through a variable resistance network generally 68 whereby the level of the signal may be adjusted. In the illustrated circuit, the continuous signal delivered to the amplifier circuit generally 64 is derived from the B source, and thus the amplifier circuit is selected to provide 180 phase change to deliver a positive signal for thyratron 52. The input 62 and output 63 of the second integrating means are also crossed by a capacitance 69 which causes the amplifier circuit to integrate the input signal. The second thyratron 52 has a grid 70 connected to the output 63 of the second integrating means. A cathode 72 of the second thyratron is connected through a variable resistance 73 to the ground terminal of the DC. power supply. Thus by appropriate adjustment of the cathode resistance 73 and the signal resistance network 68 the time required for the second thyratron 52 to fire can be adjusted. This time is always set to be somewhat greater than the longest expected production time.

The second thyratron 52 also includes a suppressor network consisting of a suppressor grid 74 connected in parallel with the cathode 72, through a resistance 75, to the B+ DC. power supply. In FIGURE 1 it may be followed that upon reaching the proper condition the second thyratron 52 will fire and permit current to flow between the cathode 72 and plate 53, thus energizing the coil of the second D.C. powered relay 55 to close the relay switches. These switches consist of the aforementioned first switch 61 and a second switch 77.

As previously explained, the first switch 61 is connected in series with the fourth relay switch 50 of the first D.C. powered relay 34 across the amplifier circuit 64 input and output terminals 62, and 63, respectively; and when both switches are closed, the second integrating means will be shorted to halt that integrating function. Since the second D.C. powered relay 55 can only be energized after the first D.C. powered relay 34 has been energized (closing all of its associated switches, including switch 48), the dwell integrator will cease functioning the moment that the first switch 61 of the second D.C. powered relay 55 is closed.

At the same time, the second switch 77 of the second D.C. powered relay 55 will close to connect a suppressor grid 81 and resistor 82 network and a plate 83 of a third thyratron to the B+ terminal. Also a solenoid coil of a third D.C. powered relay 85 is thereby connected to the 13+ power supply in series with the plate 83 of the third thyratron 80. A grid 86 of the thyratron S0 is connected directly to DC. ground; and a cathode 87 of the latter thyratron is connected to the ground terminal of the DC power supply 22 through a resistor 88. The latter resistance, however, can be partially by-passed through a lead 89 connected to a second momentary acting switch 90 and thence to the ground terminal of the D.C. power supply 22.

The second momentary acting switch 90 is also mounted on the slicing apparatus 16 to be operated momentarily once each revolution of the involute knife 18. This switch 90 is fixed in a position, similar to that of the first momentary acting switch 46, so that it will be actuated in advance of the point at which the involute blade 18 would commence cutting material 13 passed therebeneath. However, as with switch 46, the exact position may vary substantially with operating characteristics of the slicing machine.

The third thyratron 80 is adjusted so that it will fire briefly immediately upon each closing of the second momentary acting switch 94). However, since the plate 83 is connected to the DC. power supply 22 only upon completion of the dwell integrator function, current will pass between cathode 37 and plate 83 only after a full slicing and dwell cycle has been completed.

The third D.C. powered relay 85, which will thus be energized upon the firing of the third thyratron 8t actuates a single normally closed switch 92, previously mentioned in connection with the coil of the first D.C. relay 34. This switch is normally closed to connect the plate 37 of the first thyratron 36 and the coil of the first D.C. powered relay 34 to the B+ DC. power terminal. Upon energization of the third D.C. powered relay 255 this switch is opened to disconnect the first D.C. powered relay 34, and thereby open the four switches operated by that relay.

This action concurrently causes: the production integrator 26 to be unshorted so that it can recommence integrating a signal from the potentiometers 11; the dwell integrator 64 to be similarly unshorted; power to be disconnected from the second thyratron plate 53 and second D.C. powered relay 55; the dwell solenoid 59 on the slicing feed apparatus to be disconnected; and the production solenoid 57 reconnected across A.C. power supply to cause the fiow control valve to be thrown to a position permitting fiuid to enter the feed device and recommence advancement of the material 13 to the slicing blade 18.

It will also be seen in FIGURE 1 that upon de-energization of the solenoid of the second DC. powered relay 55 the solenoid of the third D.C. powered relay 85 is also disconnected, thus closing the switch 92 associatedwith the latter. The plate 37 and relay solenoid of the first thyratron 36 are immediately reconnected thereby, to the 13+ terminal of the'DC. power supply 22. Accordingly, the device is not only in condition to immediately recommence integration of both production and dwell functions but also is reset to detect and act upon the signals produced thereby.

The control system also includes a component for automatically disabling both integrator means at the time that a complete unit of material has been fed to the slicing blade. That is, for example in the slicing of bacon slabs, at the time the end of a slab reaches the cutting knife 18 the hydraulic pusher 19 must be withdrawn and a new slab inserted for further slicing. For this purpose a limit switch 94 physically located adjacent the path of material 13 near the blade 18, is connected between one terminal of the A.C. power supply 58 and the solenoid of an A.C. powered relay 95. The latter relay includes three switches. The first switch Q6 of this relay is normally open, but when the relay is energized it closes to complete a holding circuit to the AC. power terminal whereby the limit switch 94 may be disengaged and current maintained to the solenoid of relay 95. The two other switches include the previously mentioned shorting switch 97 for the production integrator (in parallel with switch 35) and another shorting switch 98 for the dwell integrator (in parallel with series connected switches 5t! and 61). Thus 10 when the A.CL powered relay is energized both integrating means will be shorted.

In FIGURE 1 it will also be seen that the AC. powered relay 95 is connected to the opposite AC. power terminal through another switch 101 operated by a second A.C. powered relay hit The latter switch 101 is normally closed when the relay is unenergized, and will be opened only upon energization of the latter. This is accomplished through the fact that the solenoid coil of the latter relay 1% is connected across an A.C. power supply in series with a manually operated switch 102. Thus when switch 102 is actuated, the solenoid of relay ltli) will be energized to break the A.C. circuit to the solenoid of relay 95. When relay 95 is unergized, switches 97 and 98 open and both amplifier circuits 26 and 64 commence integrating.

The solenoid of the second A.C. relay 1%, when energized, simultaneously closes a normally open second switch 103 to directly connect the cathode 39 of the first thyratron 36 to the ground terminal of the DC. power supply 22. This will cause the first thyratron 36 to fire, thus providing means for a manual initiation of the control cycle through operation of switch 102.

In operating a bacon slicing machine equipped with the present control system, an operator actuates, by manual control of the hydraulic feed, the machine to withdraw the hydraulic pusher 19 from the slicing blade 18 and inserts the first bacon slab 13. The operator then advances the slab into the knife 18 to' sever sufficient slices to obtain a squared end, and then closes the switch 102. This causes the thyratron 36 to fire and dwell solenoid 59 to be energized, thus initiating an automatic cycle controlled only by the dwell integrator. The normal dwell integrator signal period will provide sufiicient time for the imperfect slices to be moved clear of the slicer before commencement of the first acceptable group. Subsequently, when a slab is completely sliced, the usual hydraulic feed will automatically return the pusher for insertion of the succeeding slabs.

During automatic operation, drafts of a varying number of slices, each draft comprising the same total volume and, therefore, total weight, will be severed and interspaced by brief periods of time during which the feed mechanism ceases advancement of the bacon into the involute knife 18. In practice it will usually be found that the variation in cross-sectional dimension of a bacon slab will not be so great as to vary the total number of slices per draft by more than one or two items. The total quantity of bacon per draft, however, may be adjusted by means of the variable resistor 29 which establishes the upper limit of the variable signal sent to the first integrating means 26 controlling the period of production.

Similarly, as previously explained, the resistor network 68 controlling the base level of the. signal impressed upon the second integrating means 64 (thus controlling the total slicer cycle including both production and dwell) can be adjusted to establish the total duration of the complete slicing cycle for drafts of various amounts.

At the time that the hydraulic pusher 19 advances to the fully extended position and the last of the bacon slab is sliced, the pusher will strike the limit switch 94 (and at the same time will actuate a hydraulic reversing mechanism which is not shown) causing the control system to short both first and second integrating means 26, 64, and thereby stop the operation of the control system. The operator then again inserts a new bacon slab and causes the first few slices to be removed, repeating the previously described operations.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made Without departing from the spirit and scope thereof. For instance, well-known pneumtaic and/ or hydraulic elements could readily be substituted for comparable electrical elements above described, thus using the present teachings to construct a functionally equivalent mechanical device ca- 1 l pable of carrying out the present method. Therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. An improved method of controlling a feeding operation in accordance with an amount fed and a repeating operation performed on said amount being fed, said method comprising the steps of: developing and increasing a signal representing the volume of the material having passed a given point; producing a constant signal momentarily once during each repetition of an operation on said material; and interrupting the feeding of said material upon the sum of said increasing signal and said constant signal momentarily reaching an established magnitude.

2. An improved method of controlling a feeding operation in accordance with an amount fed and a repeating operation performed on said amount being fed, said method comprising the steps of: feeding a stream of material at a given lineal speed in a given direction; sensing at least one dimension of said stream, and changes in said dimension, at a point along said stream; producing a first signal varying in accordance with the sensed dimension; integrating said first signal against a function of said speed to produce an increasing signal changing in direct relation to the volume of material moved past said point; producing a constant signal momentarily once during each repetition of an operation on said material; and interrupting the feeding of said material at the time the sum of said increasing signal and said constant signal momentarily reaches an established value.

3. An improved method of controlling a feeding operation in accordance with an amount fed and a repeating operation performed on said amount being fed, said method comprising the steps of: feeding a material in a given direction at a given lineal speed; sensing at least two dimensions of said material, and changes in said dimensions, at a point in said direction in advance of the location at which the repeating operation is performed; producing a first signal varying in accordance with the average value of said sensed dimensions; integrating said first signal against a function of said given speed and producing an increasing signal changing in direct relation to the volume of material moved past said point; producing a constant signal momentarily once during each repetition of an operation on said material; and interrupting the feeding of said material at the time the sum of said increasing signal and said constant signal momentarily reaches an established value.

4. An improved method of controlling a feeding operation in accordance with an amount fed and a repeating operation performed on said amount while being fed, said method comprising the steps of: feeding a material at a given lineal speed in a given direction; sensing at least two dimensions of said material, and changes in said dimensions, at a point in said direction in advance of the location at which said repeating operation is performed; producing a first signal varying in accordance with the average value of said sensed dimensions; causing said first signal to be integrated as a function of said speed to thereby produce an integrated signal increasing in direct relation to the volume of material moved past said point; producing a constant signal momentarily once during each repetition of an operation on said material; detecting both said increasing signal and said momentary constant signal in a single detecting means to cumulate the effect of said signals; and interrupting the feeding of said material at the time the cumulated effect of said increasing signal and said constant signal momentarily reaches an established value.

5. An improved method of controlling a bacon slicing operation in accordance with an amount of bacon fed past a slicing means and the position of said slicing means with respect to the bacon, said method comprising the steps of: feeding a slab of bacon toward a slicing means at a given lineal speed; sensing two cross-sectional dimensions of said bacon slab, and changes in said dimensions, along a line at right angles to the direction of feed just in advance of the slicing means; producing a first direct current po tential as a cross-sectional signal varying in accordance with the average value of said sensed dimensions; integrating the cross-sectional signal against a function of said speed to produce an increasing direct current potential as a volume signal increasing in direct relation to the amount of material moved past said point; producing a constant direct current potential as a momentary signal once during each cycle of said slicing means; applying both said volume signal and said momentary signal to an electrical valve which Will change conditions upon the cumulative effect of said signals reaching an established value; and interrupting the feeding of said bacon slab into said slicing means at the time said electrical valve changes condition.

6. An improved control system for a slicing machine having a slicing element and a feed for advancing material in a given direction and at a given speed thereto, said control system comprising: sensing means between said feed and said slicing element, said sensing means positioned to detect dimensions of the material and changes therein; first signal means connected to said sensing means, said first signal means being operable to produce a first signal variable in accordance with said dimensions of said material; integrating means connected to said first signal means, said integrating means acting to continuously integrate said first signal produced by said signal means against said speed to develop a second increasing signal changing in direct relation to the volume of material moved past said sensing means; a second signal means associated with the slicing element, said second signal means adapted to momentarily produce a constant signal of a given magnitude once during each complete cycle of said slicing element; detecting means connected to said integrating means and said second signal means, said detecting means adapted to change condition upon the cumulation of said second and said constant signals reaching a specified level; and regulating means connected between said detecting means and the feed means to cause interruption of said feed upon such change in condition of said detecting means.

7. The control system of claim 6 including: a continuous signal means, said means being adjustable to produce a continuous and constant signal of selected magnitude; a second integrating means connected to said continuous signal means, said second integrating means acting to continuously integrate the continuous signal against time so as to develop a uniformly changing signal in direct relation to an imaginary volume comparison; a second detecting means electrically connected to said second integrating means and to said regulating means, said second detecting means adapted to change condition upon the uniformly changing signal reaching a fixed standard of comparison, whereby upon said change in condition the regulating means will be caused to release the interruption of said feed; and reset means connected to both said detecting means and to reverse the change of condition of both of said detecting means and to thereby recycle both of said integrating means upon the change in condition of said second detecting means.

8. In a slicing machine having a slicing element and a feed for advancing material in a given direction and at a given speed thereto, a control system comprising: followers suspended between said feed and said slicing element, said followers being positioned to be moved in accordance with changes in the dimensions of the material; first potentiometers connected to said followers, said potentiometers being varied by the movement of said followers to produce a first electrical signal variable in accordance with said dimensions of said material; an amplifier means electrically connected to said potentiometers, said amplifier means acting to continuously integrate said first signal, produced by said potentiometers, against said speed to develop a second increasing signal changing in direct relation to the volume of material moved past said followers; a momentary action switch associated with the slicing element, said switch adapted to be momentarily closed by said slicing element to thereby produce a constant signal of a given magnitude once during each complete cycle of said slicing element; and detecting means connected to said amplifier means and said switch, said detecting means adapted to change condition upon the cumulation of said first signal and said constant signal reaching a specified level; and a solenoid connected to said detecting means and in association with said feed to interrupt said feed upon the change in condition of said detecting means.

9. An improved method of controlling a slicing operation in accordance with an amount of material fed past a slicing means, said method comprising the steps of: feeding said material at a constant speed toward said slicing means to that all slices severed thereby are of uniform thickness; sensing at least one cross sectional dimension of said material, and changes therein, normal to the path thereof; producing a signal representing the volume of said material having passed a given point on said path; and completely interrupting the feeding of said material for brief periods upon said signal representing a desired vol ume of said material.

10. An improved method of controlling a bacon slicing operation in accordance with an amount of bacon fed past a slicing means, said method comprising the steps of feeding a bacon slab at a constant speed along a path toward said slicing means so that all slices severed thereby are of uniform thickness; sensing at least one cross sectional dimension of said slab, and changes therein, normal to the path thereof at a point on said path just in advance of said slicing means; producing a signal in proportion to the dimension thus sensed; integrating said signal against said constant speed whereby a signal representing the volume of said slab having passed said point is produced; and completely interrupting the feeding of said slab for brief periods upon said last mentioned signal reaching a level representing a desired volume of said bacon slab.

11. A control system for a slicing machine having a slicing element and a feed for advancing material in a given direction and at a given speed thereto, said control system comprising: sensing means between said feed and said slicing element, said sensing means positioned to detect cross-sectional dimensions of the material and changes therein; first signal means connected to said sensing means, said first signal means being operable to produce a first signal variable in accordance with said dimensions of said material; integrating means connected to said first signal means; said integrating means acting to continuously integrate said first signal produced by said signal means against said speed to develop a second increasing signal changing in direct relation to the volume of material moved past said sensing means; detecting means connected to said integrating means, said detecting means adapted to change condition upon said second signal reaching a specified level; and regulating means connected between said detecting means and the feed means to cause interruption of said feed upon said change in condition of said detecting means.

References Cited in the file of this patent UNITED STATES PATENTS 1,972,586 Etter et al Sept. 4, 1934 1,976,823 Mahler Oct. 16, 1934 2,966,186 Garapolo Dec. 27, 1960 3,010,499 Dahms et a1 Nov. 28, 1961 

6. AN IMPROVED CONTROL SYSTEM FOR A SLICING MACHINE HAVING A SLICING ELEMENT AND A FEED FOR ADVANCING MATERIAL IN A GIVEN DIRECTION AND AT A GIVEN SPEED THERETO, SAID CONTROL SYSTEM COMPRISING: SENSING MEANS BETWEEN SAID FEED AND SAID SLICING ELEMENT, SAID SENSING MEANS POSITIONED TO DETECT DIMENSIONS OF THE MATERIAL AND CHANGES THEREIN; FIRST SIGNAL MEANS CONNECTED TO SAID SENSING MEANS, SAID FIRST SIGNAL MEANS BEING OPERABLE TO PRODUCE A FIRST SIGNAL VARIABLE IN ACCORDANCE WITH SAID DIMENSIONS OF SAID MATERIAL; INTEGRATING MEANS CONNECTED TO SAID FIRST SIGNAL MEANS, SAID INTEGRATING MEANS ACTING TO CONTINUOUSLY INTEGRATE SAID FIRST SIGNAL PRODUCED BY SAID SIGNAL MEANS AGAINST SAID SPEED TO DEVELOP A SECOND INCREASING SIGNAL CHANGING IN DIRECT RELATION TO THE VOLUME OF MATERIAL MOVED PAST SAID SENSING MEANS; A SECOND SIGNAL MEANS ASSOCIATED WITH THE SLICING ELEMENT, SAID SECOND SIGNAL MEANS ADAPTED TO MOMENTARILY PRODUCE A CONSTANT SIGNAL OF A GIVEN MAGNITUDE ONCE DURING EACH COMPLETE CYCLE OF SAID SLICING ELEMENT; DETECTING MEANS CONNECTED TO SAID INTEGRATING MEANS AND SAID SECOND SIGNAL MEANS, SAID DETECTING MEANS ADAPTED TO CHANGE CONDITION UPON THE CUMULATION OF SAID SECOND AND SAID CONSTANT SIGNALS REACHING A SPECIFIED LEVEL; AND REGULATING MEANS CONNECTED BETWEEN SAID DETECTING MEANS AND THE FEED MEANS TO CAUSE INTERRUPTION OF SAID FEED UPON SUCH CHANGE IN CONDITION OF SAID DETECTING MEANS.
 9. AN IMPROVED METHOD OF CONTROLLING A SLICING OPERATION IN ACCORDANCE WITH AN AMOUNT OF MATERIAL FED PAST A SLICING MEANS, SAID METHOD COMPRISING THE STEPS OF: FEEDING SAID MATERIAL AT A CONSTANT SPEED TOWARD SAID SLICING MEANS TO THAT ALL SLICES SEVERED THEREBY ARE OF UNIFORM THICKNESS; SENSING AT LEAST ONE CROSS SECTIONAL DIMENSION OF SAID MATERIAL, AND CHANGES THEREIN, NORMAL TO THE PATH THEREOF; PRODUCING A SIGNAL REPRESENTING THE VOLUME OF SAID MATERIAL HAVING PASSED A GIVEN POINT ON SAID PATH; AND COMPLETELY INTERRUPTING THE FEEDING OF SAID MATERIAL FOR BRIEF PERIODS UPON SAID SIGNAL REPRESENTING A DESIRED VOLUME OF SAID MATERIAL. 